We shall study the genetic basis of cell motility and endocytosis, using the lower eukaryote Dictyostelium discoideum. Mutants that are non-motile or which fail to endocytose bacteria will be isolated. Genetic complementation, linkage, and reversion analyses will be carried out to determine the genetic complexities of these processes. We shall isolate plasma membrane preparations that contain the cytoskeleton and use two dimensional gel analysis of wild-type and mutant cell to search for physically altered components of the membrane and cytoskeleton. These studies will be broadly relevant to studies of plasma membrane function and structure, but in particular, they should provide useful information relevant to the motile behavior of leukocytes in the immune response.